1. Field of the Invention
The present invention relates generally to a vehicle and more specifically to a wheel bearing unit and a brake drum.
2. Description of Related Art
Drum brakes may include wheel bearing units that support a wheel on an axle of a motor vehicle. In addition, when used with an antilock brake system rotational speed sensors are installed with or included on the wheel bearing units to determine the rotational speed of an individual wheel. Such rotational speed sensors do not directly determine the rotational speed of the wheel itself, but instead of a transmitter ring rotating synchronously with the wheel. The transmitter ring is arranged in a transmitter chamber which is typically vented.